The Rover-Landers of BC

I would be inclined not to give up on the master cylinder yet. When I bled my completely renewed system on my my '57, it took ages to get all the air out. The only component I rebuilt was the master cylinder, just as you did, from what it sounds like. For a simple system, it was horrible to bleed.

What I ended up doing was pushing fluid via the master cylinder using low pressure compressed air (about 10-15psi). I put a rubber tip on an air nozzle and put it firmly on the vent hole of the reservoir cap. One person applying air and maintaining fluid level, the other cracking open the bleeder screws. Leave the pedal upright and make sure it is adjusted for proper freeplay. You still need to push a lot of fluid through doing this, but it worked for me. I have had 3 years of one push brakes on my daily ser1 after this.

Best of luck

Hi,
The way I always figured out my series brakes is simple.
Get your self 4 vice-grips, tape over the jaws with electrical tape so they cant do any damage. Clamp one vice-grip on each flexible brake hose to each wheel. Try the brakes, if pedal is hard then master cylinder is ok.
Next remove one vice-grip from the first wheels flexible brake house. Try the brakes again, if hard then remove the second vice-grip and try the pedal again.... and so on.
This method, although not fool proof should narrow the fault down to the problem area.
I have also seen "no pedal pressure" arising from other not so obvious issues, such as, incorrect size brake shoes installed, or brake shoes installed incorrectly (there is a lead shoe and a following shoe in each drum if I remember right.) Also your drums may be worn (or been skimmed out) and now are oversized. I have also seen worn flexible hoses that bubble out when the brake pedal is pushed instead of pushing the brake pistons out.
Try the above method first, see if you can narrow down your search,
good luck, let us know how you get on,
Andy